摘要
对承受支管轴力和主管轴力的N型圆钢管相贯节点(JD-A),垫板加强节点(JD-B),主管填充混凝土节点(JD-C),主管填充混凝土和垫板加强节点(JD-D)试件进行了极限承载力试验。介绍了试件的设计、加载制度和试验步骤,提出了确定试件极限承载力的方法,观察到了试验现象,得到了主要试验结果。
试验结果显示:JD-A和JD-B试件的破坏模式为主管表面的塑性失效破坏,JD-C试件的破坏模式为受压支管的局部屈曲破坏,JD-D试件试件的破坏模式为加强垫板的剪切破坏。计算表明:试验所得的JD-A试件的承载力与我国规范(GB50017-2003)公式及Packer教授建议公式的计算结果的比值分别为:0.97和1.05。说明对于材料的屈服强度超过355 Mpa的N型圆管相贯节点,我国规范公式得到的极限承载力结果仍比较可靠。主管填充混凝土能大大增强主管径向刚度,从而显著提高节点极限承载力,加强垫板对节点承载力提高幅度不大,只能在一定程度上减小主管壁的变形,而当主管径向刚度已经很大时,对主管加垫板可能反而降低节点的极限承载力。考虑到对于圆钢管加强节点,垫板加工和焊接难度较大,实际成本高,在对自重要求不高的结构中,对钢管填充混凝土是提高节点承载力应优先考虑采取的加强措施。试验结果也说明在空心管节点和加强节点的设计中,关键就是控制主管径向刚度和支管轴向刚度的比值,选取最佳比值,使主管和支管均发挥最大使用率。
采用ANSYS程序中四节点板壳单元对试验节点进行了弹塑性、大挠度有限元分析,比较试验和数值模拟研究所得的受压支管荷载-主管管壁变形曲线,二者吻合较好,说明试验结果可靠,研究中采用有限元分析方法可运用于实际工程的理论计算中。
有限元分析所得的JD-A、JD-B、JD-C和JD-D试件的承载力与试验结果的比值分别为:1.05,1.04,0.97,1.08。二者间JD-D试件的承载力相差较大的主要原因是有限元计算时JD-D试件发生的是和JD-C试件相同的受压支管局部屈曲破坏,而试验中JD-D是因加强垫板突然的剪断破坏。比较各节点试件的应力分布规律和塑性发展过程,发现垫板的加强原理是借助于垫板的厚度效应和传力作用,将支管荷载扩散到更大的主管表面,使极限承载力也分别得到相应的提高。在主管内填充混凝土的加强原理是当沿主管受压支管相贯线周围的主管壁屈服后,核心混凝土承受支管传来的绝大部分荷载,使节点的极限承载力得到显著提高。
Experiments on static behavior of a tubular N-joint(JD-A),a plate reinforced tubular N-joint(JD-B), a concrete filled tubular N-joint(JD-C) and a N-joint reinforced both by concrete and plate(JD-D) under the axial compressive stress on brace and chord were carried out. The design of test specimens、the loading scheme and the testing steps are introduced, methods to estimate the ultimate bearing capacity of the four joints are proposed, the phenomena and the main results of tests are obtained.
Experimental results showed that the failure mode of specimen JD-A and JD-B were plastic fracture at the connecting face of chord;the failure mode of specimen JD-C was local buckling failure of the brace,which bear the weight of compressive stress;and the failure mode of the specimen JD-D was rupture of the reinforce plate. The calculation indicates that the ratio of the test value of ultimate capacity of specimen JD-A to the result obtained from code design formula is 0.97,and to the formula suggested by professor Packer is 1.05,it illuminate that for tubular N-joints,even if whose material yield-point preponderate over 355 Mpa,credible results of the ultimate capacity of the joints can still be obtained from the code design formula. The calculation also indicates that the ultimate capacity of joints can be remarkably enhanced by filling concrete in chord, and can be only enhanced to a certain extent by welding a reinforce plate on tubular wall of chord,for filling concrete can considerably augment the ratio of radial stiffness of chord to axial stiffness of braces,whereas the reinforce plate can’t. While welding a reinforce plate on tubular wall of chord may weaken the ultimate capacity of the joint when the radial stiffness of chord is sufficient. For reinforce tubular joints,considering the operational difficulties in machining and welding reinforce plate may aggrandize practical cost , filling concrete be given preferential consideration to reinforce tubular joints when within the confines of deadweight of the structure. Therefore the key point in designing of tubular joints and reinforced tubular joints is control the ratio of radial stiffness of chord to axial stiffness of braces to make best use of chord and braces.
Making use of finite element package program ANSYS,in which four nodes shell element was employed,elastic-plastic large deflection finite element analysis(FEA) of the experimental joints was conducted. Compared the curves of load in compressive brace with deformation in tubular wall of chord obtained from experiments and finite element analysis,there is a good agreement between the experimental and analytical results,it proves experimental results are reliable,and the method employed in FEA can be used in practical project.
The ratio of FEA value of ultimate capacity of specimen JD-A,JD-B,JD-C and JD-D to the results obtained from code design formula is 1.05,1.04,0.97 and 1.08. The main reason for the relative discrepancy of specimen JD-D is that the failure mode of FEA result is local buckling failure of the brace, which is different from test result. Compared the stress distribution and propagation of plasticity of the four joints find that the reinforce plate can diffuse load from braces to lager face of joint’s chord and enhance ultimate capacity of the joints, filling concrete can bear most load from braces after connecting zone of chord wall yielded, thus remarkably enhance ultimate capacity of the joint.
引文
[1] 陈以一,陈扬骥 . 钢管结构相贯节点的研究现状 . 见:管结构技术交流论文集 .西安:空间结构委员会,2001,11:227-234.
[2] Packer J A,Henderson J E, Cao J J. 空心管结构连接设计指南[M]. 北京 :科学出版社,1997.
[3] 沃登尼尔. 钢管截面的结构运用[M]. 上海:同济大学出版社. 2004,5-13.
[4] 日本建筑学会. 钢结构设计施工指南及解说[M]. 丸善株式会社,1990.
[5] GB50017-2003 钢结构设计规范[S]. 北京:中国计划出版社,2003.
[6] Lalani M. Developments in Tubular Joints Technology for Offshore Structures[J]. 2nd International Offshore and Polar Engineering Conference,1992.
[7] 朱邵宁. 圆钢管相贯节点承载力分析与足尺试验研究[D]. 湖南:湖南大学,2003.
[8] 吴昌栋,陈云波. 钢管结构在建筑工程中的运用[J]. 工业建筑,1997.
[9] 丁芸孙 . 圆管结构相贯节点几个设计问题的探讨 [J]. 空间结构, 2002, 8(2):56-64.
[10] 武振宇,张耀春 . 直接焊接钢管节点静力工作性能的研究现状. 哈尔滨建筑大学学报,1996,29(6):102-109.
[11] 宋彧，李丽娟，张贵文. 建筑结构试验. 重庆:重庆大学出版社,2001:14-19.
[12] 李忠献. 工程结构试验理论与技术. 天津:天津大学出版社,2004,3.
[13] 完海鹰,王梅. K 型管节点静承载力研究[J]. 工业建筑增刊,2001,413-416.
[14] Gibstein M B. The Static Strength of T joints Subjected to in-plane Bending[J]. Det Norske Veritas Report,1976:76-137.
[15] Sparrow K D,Stamenkovic A. Experimental Determination of the Ultimate Static Strength of T joints in Circular Hollow Steel Sections Subjects to Axialand Mement[J]. Proc.Int.Conf.,Joints in Structural Steel Work,Teeside,1981.
[16] Kurobane Y. Ultimate Resistance of Unstiffened Tubular Joints[J]. Struct.Engrg, ASCE ,1984, 110(2): 385-400.
[17] Makino Y. Experimental Study on Ultimate Capacity and Deformation for Tu-bular Joints. Doctoral dissertation,Osaka University,1984.
[18] Scola J, Redwood R G. Behaviour of Axially Loaded Tubular TT-Joints[J]. J.Construct Steel Research,1990,vol 16.
[19] Zhao X L,Hancock G J,Square and Rectangular Hollow Sections Subject to Combined Actions[J]. J.Struct. Engrg.,ASCE,1991,117(8): 2258-2277.
[20] Paul J C. Ultimate Resistance of Unstiffened Multiplanar Tubular TT-and KK-Joints[J]. J.Struct.ASCE,1994,120 (10):2853-2870.
[21] Makino Y,Kurobane Y,Ochi K,Vegte G J,Wilmshurst S R. Database ofTest and Numerical Analysis Results for Unstiffened Tubular Joints. IIW Doc,XV-E-96-220,1996.
[22] Morgan M R,LEE M M K,Stress Concentration Factors in Tubular K-Joints under Inplane Moment Loading[J],J.Struct.Engrg.,ASCE,1998,124(4):382-390.
[23] Soh C K,Chan T K,Yu S K. Limit Analysis of Ultimate Strength of Tubular X-Joints[J] . J. Struct. Engrg.,ASCE,2000,126(7):790-797.
[24] Cofer W f,et al. Analysis of Welded Tubular Connection Using Continum damage Mechanics[J]. J.Struct.Engrg,ASCE,1994,118 (3):828-845.
[25] 陈继祖,陆化普. 焊接管节点设计承载力公式研究[J].大连工学院学报,1996,25(2):47-52.
[26] 陈铁云,朱正宏,吴水云 . 塑性节点法的研究及其在薄壳结构中的应用[J]. 计算结构力学及其应用,1991,8(3):242-248.
[27] 杨国贤,陈延国. 受拉 T 型管节点静承载力分析的实用计算法[J]. 大连工学院学报,1987,26(2):101-106.
[28] 张君,武秀丽. 空间 XK 型圆钢管相贯节点极限承载力非线性有限元分析.石家庄铁道学院学报,2005,18(2):64-68.
[29] 陈以一,沈祖炎,詹深等 . 直接汇交节点三重屈服线模型及试验验证[J]. 土木工程学报,1999, 32(6):26-31.
[30] 陈以一,王伟,赵宪忠等 . 圆钢管相贯节点抗弯刚度和承载力实验[J]. 建筑结构学报,2001,22(6):25-30.
[31] 同济大学钢结构研究室. 成都双流机场扩建工程航站楼钢结构屋盖结构试验研究与分析一相贯节点试验研究报告,2000.
[32] 詹深. 空间直接焊接圆钢管节点足尺试验研究[D]. 上海:同济大学,2000.
[33] 武振宇,武胜. 弦杆轴力作用下不等宽 K 型间隙方管节点性能研究[J]. 建筑结构,2004,34(5):14-17.
[34] 武胜,武振宇. 等宽 K 型间隙方管节点静力工作性能的研究[J]. 哈尔滨工业大学学报,2003,35(3):269-275.
[35] 武胜,武振宇. 不等宽 K 型间隙方管节点静力工作性能研究[J]. 哈尔滨工业大学学报,2003,35(5):513-519.
[36] 武振宇,武胜,张耀春. 不等宽 K 型间隙方管节点承载力计算的塑性铰线法[J]. 土木工程学报,2004,37(5):1-6.
[37] 张志良,沈祖炎,陈学潮. 方管节点极限承载力的非线性有限元分析[J].土木工程学报,1990,23(1):12-22.
[38] 沈祖炎,张志良. 焊接方管节点极限承载力计算[J]. 同济大学学报,1990,l8(3):273-279.
[39] 刘建平,郭彦林,陈国栋. 方圆相贯节点极限承载力研究. 建筑结构,2001,31(8):21-24.
[40] 刘建平,郭彦林. K 型方、圆相贯节点的极限承载力非线性有限元分析. 建筑科学,2001,17(2):50-53.
[41] 刘建平,郭彦林. 管节点弹塑性大挠度有限元分析. 青海大学学报(自然科学版),2001,19(1):38-42.
[42] Tebbett,Beckett I E,Billington C D,The Punching Shear Strength of Tubular Joints Reinforced with a Grouted Pile [J]. Proc.Offshore Technology Conf. Houston,Texas:Offshore Technology Conf.Assoc.,1979.
[43] Packer J A.Concrete Filled HSS Connections[J].Journal of structural Engineering,ASCE,1995,(3):458-467.
[44] Sakai Y,Hosaka T,Isoe A. Experiments on concrete filled and reinforced tubular K-joints of truss girder[J]. Journa1 of Constructiona1 Steel Research,2004,(60):683-699.
[45] 张峰,陈扬骥,陈以一等 . 内加劲环的设置对钢管节点性能的影响[J]. 空间结构,2004,l0( 7 ):51-56.
[46] 吴庆,周明智. T、Y 型方圆相贯管节点极限承载力有限元分析[J]. 淮南工业学院学报,2002,22(4):19-22.
[47] Kim,Rasmussen J R, Ben Young,Tests of X- and K- Joints in SHS Stainless Steel Tubes. Journal of Structural Engineering,2001,127(10):1173-1182.
[48] 姜晋庆等. 结构弹塑性有限元分析[M]. 北京:宇航出版社,1990.
[49] R.D.库克. 有限元分析的概念和应用[M]. 北京:科技出版社,1989.
[50] 王勋成等. 有限单元法基本原理和数值方法[M]. 北京:清华大学出版社,1995.
[51] 王国强. 实用工程数值模拟技术及其在 ANSYS 上的实践[M]. 西安:西北工业大学出版社,2000.
[52] 刘建平. 钢管相贯节点的承载力性能研究[D]. 北京:清华大学,2000.
[53] 王仁,熊祝华,黄文彬. 塑性力学基础[M]. 北京:科学出版社,1998.
[54] 赵均海,王敏强,魏雪英. 高等有限元[M]. 武汉:武汉理工大学出版社,2004.
[55] 郑天霞,邹时智,杨文兵等. 非线性结构有限元计算[M]. 长沙:华中理工大学出版社,1996.
[56] 沈祖炎等 . 上海市八万人体育场屋盖的整体模型和节点试验研究[J]. 建筑结构学报,1998,19(1):1-10.
[57] Yura J A,etal. Ultimate Capacity Equations for Tubular Joints[J]. Proc Offshore Technol,Conf,1980.
[58] Lu L H,Winkel G D,Waraenier Y J,Deformation Limit for the Ultimate Strength of Hollow Section Joints[J].Tubular Structures VI,Rotterdam:Balkema,1994,341-347.
[59] 龚曙光. ANSYS 基础运用与范例解析[M]. 北京:机械工业出版社,2003.
[60] 龚曙光. ANSYS 操作命令与参数化编程[M]. 北京:机械工业出版社,2004.
[61] 祝效华,余志祥. ANSYS 高级有限元范例精选[M].北京:电子工业出版社,2004.
[62] 陈以一,陈扬骥等. 圆钢管空间相贯节点的实验研究[J]. 土木工程学报,2003,36(8):24-30.
[63] 赵宏康,戴雅萍,吕西林. 苏州国际博览中心屋盖结构分析和并联 K 形圆钢管相贯节点研究[J]. 建筑结构学报,2006,27(8):51-60.
[64] 邵永波,LIE Seng-Tjhen. K 节点应力集中系数的试验和数值研究方法[J]. 工程力学,2006,23(增刊 I):79-85.
[65] 舒兴平. 高等钢结构分析与设计[M]. 北京:科学出版社,2004.